1. Field of the Invention
The present invention relates to a hands free kit for a car phone or mobile phone used in a car, and more particularly, to an apparatus for generating speech sounds of a short message received by the mobile phone by means of a digital signal processor (DSP).
2. Description of the Related Art
A hands free kit for a car phone or portable mobile phone used in a car enables the driver to safely communicate through the mobile phone without holding the phone, e.g., while both hands are on the steering wheel. (As used hereafter, the term “mobile phone” applies to both a dedicated car phone and a portable mobile phone.) The hands free kit employs a half-duplex circuit to transmit/receive audio signals to/from the handset of the mobile phone through transmit and receive lines, respectively. The half-duplex circuit functions to prevent sounds from the speaker from being inputted to the microphone, i.e., to prevent feedback.
A conventional hands free kit performs the communication function only when the driver has established the communication path between the handset and the hands free kit by manually operating a key on the handset. In order to eliminate such manual handset operation, the hands free kit has recently been provided with a voice control means to control the functions of the handset and to dial by voice. This feature is made possible by equipping the hands free kit with speech recognition technology embodied by a DSP therein.
Mobile phone handsets have been furnished with short message service (SMS) from communication service providers. The SMS is used to transmit a short message to the mobile phone from a caller or broadcasting service, which is displayed on the mobile phone handset display in characters. When receiving a short message, the handset outputs an audible alarm to alert the user of the reception of a message. If a short message is received while the system is operating in the hands free mode, i.e., with the handset connected to the hands free kit, the handset delivers a signal to the hands free kit indicating the same, whereupon the hands free kit sounds an alarm. The user must then manually operate the handset to read the message on the handset display. Should the user attempt to perform this task while actively driving, however, the user may create a hazardous situation.